1. Field of the Invention
The present invention relates to a means to maintain the position of two or more energetically moveable objects in a spaced relation vis-a-vis each other. More specifically, the present invention in a preferred embodiment relates to a system to maintain two marine seismic sources in a preferred, spaced orientation during continuous operation.
2. Description of the Prior Art
Marine seismic exploration often utilizes seismic sources, airguns or waterguns, pulled behind a boat over submarine horizons of perceived interest. Upon actuation, these sources create a strong, primary pressure pulse which is useful in interpreting the strata comprising the sea floor.
To enhance this primary pulse, and hence advance the geological interpretation of the sea floor, it has become common practice to simultaneously fire a number of these seismic sources. In this connection, it has been discovered that marine seismic sources selectively positioned with respect to each other optimize the creation of the primary pulse while minimizing the creation of undesired secondary pulses. This optimization, generally known as the xe2x80x9ccluster effect,xe2x80x9d relies on spacing between the sources given the parameters of volume, pressure, and depth.
In practice, however, realization of the benefits of the xe2x80x9ccluster effectxe2x80x9d has been difficult since seismic sources, due to the strong energy pulses created during actuation and recoil, are prone to substantial and energetic movements with respect to each other. Furthermore, the air bubbles created upon actuation of the marine acoustic generator ultimately collapses, forcing the sources together and thereby inducing significant damage on the gun lines and peripheral equipment.
Prior mechanical clamping systems have been designed to address this issue. Such clamping systems, however, if strong enough to prevent substantial movement of the sources with respect to each other, have generally been bulky and contribute to substantial drag on the towing source. In some instances, this drag may be of a sufficient magnitude as to foreclose their use as a towed array altogether.
Systems which are not as massive, and hence more streamlined, having been generally unable to achieve the rigidity and spacing necessary for optimization of the xe2x80x9ccluster effectxe2x80x9d. Moreover, such systems are readily damaged through consecutive recoils of the seismic sources during operation.
The present invention addresses the above identified and other disadvantages of prior art coupling systems by providing a streamlined system which secures energetic sources in a fixed relation with respect to each other. Such a system is therefore suited for use as a towed seismic source. The present system also allows for controlled, resilient deformation during actuation of the seismic source, thereby enhancing the useful life of the system.
In a general embodiment, the present invention comprises coupling means securable to one or more energetic sources, e.g., marine seismic sources; spacing means securable to the coupling means so as to maintain the energetic sources in a substantially fixed relationship with respect to each other; rotation means; and, a shock absorption means disposed between the coupling means and the spacing means so as to allow controlled resilient deformation of the system without premature deterioration and/or fatigue of its various components.
The spacing system of the present invention orients two or more energetic sources at a precise distance from each other and at an optimum separation distance to accentuate the primary pulse and minimize secondary pressure pulses. This system also serves to prevent significant displacement between the sources during actuation while absorbing energy caused, in the instance of a marine acoustic source, by the explosive force, recoil and ultimate implosion of the bubble.
The present invention presents a number of advantages over prior art systems. One such advantage is that the system presents a low profile and hence low drag when used as a towed source. This is significant where the system is to be towed through the water such as is in the case of a marine acoustic generator.
Another advantage of the present invention is that the system demonstrates greatly reduced wear due to rotation means shock absorption build into the system through controlled, resilient deformation. Yet another advantage of the present invention is its ready adaptation to a conventional energy source, which adaptation facilitating inspection and disassembly.
Other benefits and advantages will become apparent through a review of the detailed description of the preferred embodiment.